Passenger vehicles are generally configured with a mutually welded plurality of panels at the vehicle body. The stiffness of the panels is reinforced by joint numbers and formation of the inner cross-section. In order to obtain a lateral stiffness against exterior impact, a cross member having a closed cross-section is mounted and a center pillar (B-pillar) is formed in the section between the front and rear doors.
However, an excessive indentation can be made into a conventional vehicle body upon a major lateral impact due to a lack of sufficient stiffness, thus making the occupants susceptible to injury.
Thus, the vehicle floor or center-pillar is reinforced in stiffness thereof, however, the middle portion of the center-pillar has an inadequate rigidity upon a severe impact.
In the case of racing vehicles, X-shaped reinforcement pipes are occasionally installed in the vehicle body. Such pipes, however, take up a lot of room in the compartment space, resulting in inefficient use of the space in the passenger vehicles.